Heat conduction member and liquid crystal display having the same

ABSTRACT

An LCD comprises an LCD panel on which an image is formed, a light guiding plate disposed behind the LCD panel, an LED unit disposed along at least one side of the light guiding plate and providing light to the LCD panel, a bottom chassis accommodating the light guiding plate and the LED unit, and a heat conduction member disposed across an external surface of the bottom chassis from an area facing the LED unit to an area apart from the LED unit and having a higher thermal conductivity than the bottom chassis.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.2005-0031347, filed on Apr. 15, 2005, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present disclosure relates to a heat conduction member and a liquidcrystal display (LCD) having the same, and more particularly, to alightweight heat conduction member and a corresponding LCD having thesame, which exhibit improved cooling efficiency.

2. Discussion of the Related Art

A liquid crystal display (LCD) comprises an LCD panel having a thin-filmtransistor (TFT) substrate, a color filter substrate and a liquidcrystal layer disposed therebetween. The LCD panel does not emit lightby itself. Therefore, a backlight unit may be disposed behind the TFTsubstrate for providing light. The transmittance of the light from thebacklight unit depends on an alignment of liquid crystal moleculeswithin the liquid crystal layer. The LCD panel and the backlight unitare accommodated within a chassis.

The backlight unit is classified into an edge type backlight unit or adirect type backlight unit according to where a light source is disposedin the backlight unit.

The edge type backlight unit is employed in a small-sized LCD, such as,a monitor of laptop and desktop computers or a portable terminalapparatus. The edge type backlight unit comprises a light guiding platedisposed behind the LCD panel, and a reflecting sheet disposed behindthe light guiding plate. The edge type backlight unit also includes alamp unit disposed along at least one side of the light guiding plate,the lamp unit providing light to the LCD panel. Optical sheets, whichdiffuse and focus the light guided by the light guiding plate, aredisposed on the light guiding plate.

An Electro Luminescence (EL) device, a Cold Cathode Fluorescent Lamp(CCFL), a Hot Cathode Fluorescent Lamp (HCFL), an External ElectrodeFluorescent Lamp (EEFL), or an Light Emitting Diode (LED) may be used asa lamp unit.

Light emitted from the lamp unit is transformed to a surface lightsource by the light guiding plate and may be incident upon the LCDpanel.

An LED light source generates more heat than other light sources (e.g.,CCFL and EEFL). The heat from the LED causes brightness to decrease anda color shift to generate.

A radiating fin, a heat pipe and a cooling fan are used to remove theheat from the LED, but also cause the LCD to be weighty and thick.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a heat conduction memberand an LCD having the same that is light and slim and exhibit improvedcooling efficiency.

An LCD, in accordance with an embodiment of the present invention,comprises an LCD panel on which an image is formed, a light guidingplate disposed behind the LCD panel, an LED unit disposed along at leastone side of the light guiding plate and providing light to the LCDpanel, a bottom chassis accommodating the light guiding plate and theLED unit, and a heat conduction member disposed across an externalsurface of the bottom chassis from an area facing the LED unit to anarea spaced apart from the LED unit, the heat conduction member having ahigher thermal conductivity than the bottom chassis.

A thermal conductivity of the heat conduction member may be at leastabout 90 W/mK higher than that of the bottom chassis.

The thermal conductivity of the heat conduction member may be about 220W/mK or more.

A thermal conductivity of the bottom chassis may be about 130 W/mK orless.

The bottom chassis may be formed in a quadrangular shape and comprise abottom side and lateral sides formed by bending upwardly each edge ofthe bottom side. The heat conduction member may comprise a firstconducting part combined with the lateral sides and a second conductingpart combined with the bottom side.

LED units may be disposed at opposite edges of the light guiding plate,and the first conducting part may include a first portion and a secondportion respectively disposed corresponding to the LED units at theopposite edges.

The second conducting part may comprise a rectilinear area and anoblique area disposed in an oblique direction from the rectilinear area.

The first conducting part, including the first and second portions, maybe thicker than the second conducting part.

The heat conduction member may be made by using a mold.

The heat conduction member may be applied to an entire rear surface ofthe bottom chassis.

The heat conduction member may further comprise an adhesive layerdisposed on the bottom chassis.

The heat conduction member may comprise graphite.

According to an embodiment of the present invention, a heat conductionmember for a liquid crystal display comprises a first conducting partand a second conducting part extended from the first conducting part,wherein thermal conductivity of the heat conduction member is about 220W/mK or more.

The first conducting part and the second conducting part may be in aplate shape and combined in a single body to form a ‘U’ shape.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention can be understood in moredetail from the following descriptions taken in conjunction with theaccompanying drawings of which:

FIG. 1 is a perspective view of an LCD comprising a heat conductionmember according to an embodiment of the present invention;

FIG. 2 is a sectional view of the LCD shown in FIG. 1;

FIG. 3 is an enlarged view of a portion of FIG. 2 for illustrating howheat generated from an LED unit is radiated;

FIG. 4 is a perspective view of the heat conduction member shown in FIG.1; and

FIGS. 5 to 7 are perspective views of heat conduction members accordingto embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be describedmore fully hereinafter below in more detail with reference to theaccompanying drawings, in which preferred embodiments of the inventionare shown. This invention may, however, be embodied in different formsand should not be construed as limited to the embodiments set forthherein.

As shown in FIG. 1 to FIG. 4, an LCD 1 according to a an embodiment ofthe present invention comprises an LCD panel 100 on which an image isformed, a backlight unit 300 disposed behind the LCD panel 100, and atop chassis 400 and a bottom chassis 500 disposed on the LCD panel 100and behind the back light unit 300, respectively. The top and bottomchassis 400, 500 accommodate the LCD panel 100 and the back light unit300. The backlight unit 300 provides light to the LCD panel 100. A heatconduction member 600 is disposed on an external surface of the bottomchassis 500.

The LCD panel 100 comprises a TFT substrate 110, a color filtersubstrate 120 and a liquid crystal layer (not shown) disposedtherebetween.

The backlight unit 300 comprises a light guiding plate 310 disposedbehind the LCD panel 100, and a reflecting sheet 350 disposed behind thelight guiding plate 310. The reflecting sheet 350 reflects light, whichis leaked in the opposite direction of the LCD panel 100, to the lightguiding plate 310. The backlight unit 300 also comprises an LED unit 360disposed along at least one side of the light guiding plate 310. The LEDunit provides light to the LCD panel 100. The backlight unit 300 alsoincludes optical sheets 370 disposed on the light guiding plate 310. Theoptical sheets 370 diffuse and focus light guided by the light guidingplate 310.

The light guiding plate 310 has a square-plate shape and comprises anincident surface 311 on which light emitted from the LED unit 360 isincident, a reflective surface 312 forming a predetermined angle withthe incident surface 311 and facing the reflecting sheet 350, and anexiting surface 313 facing the LCD panel 100 and emitting light to theLCD panel 100.

A pair of LED units 360 are disposed parallel with each other adjacentsides of opposite incident surfaces 311 of the light guiding plate 310.The LED units 360 comprise a plurality of LED members 362 and asubstrate 361 supplying an electric signal to the plurality of LEDmembers 362.

Each LED member 362 has a quadrangular shape and comprises red, green,and blue chips and a light guiding part having silicon inside, whichemits white light toward the light guiding plate 310.

A gap pad 380 is disposed between a substrate 361 and lateral sides 521,522 of the bottom chassis 500. The gap pad 380 is a thin plate having ahigh thermal conductivity and is about 0.5 mm thick. Since the substrate361 and the bottom chassis 500 are adhered to each other via the gap pad380, heat generated from the LED unit 360 is easily conducted to thechassis 500.

Each LED member 362 may emit red, green and blue colors separately sothat light from each LED member 362 may be mixed to be incident to thelight guiding plate 310.

Optical sheets 370 comprise a diffusion film 371 having a coating layerin the form of beads, a prism film 372 disposed on the diffusion film371, and a protection film 373 disposed between the LCD panel 100 andthe prism film 372. The diffusion film 371 diffuses light from the lightguiding plate 310. The prism film 372 focuses light in the perpendiculardirection to the LCD panel 100. The protection film 373 protects the LCDpanel 100.

Two or three diffusion films 371 may be overlapped.

Typically, two prism films 372, a regular prism and an inverse prism,are used, and micro prisms formed on each prism film make predeterminedangles with respect to each other. Accordingly, light incident from thediffusion film 371 progresses vertically on the LCD panel 100, therebyforming a uniform brightness distribution.

The bottom chassis 500 is formed in a quadrangular shape and comprises abottom side 510 and lateral sides 521, 522, 523, 524 formed by bendingupwardly each edge of the bottom side 510. The bottom chassis 500 isjoined to the top chassis 400 and the backlight unit 300 is accommodatedtherebetween. On the external surface of the bottom chassis 500 isdisposed the heat conduction member 600 to radiate heat generated fromthe LED unit 360 accommodated in the bottom chassis 500. The bottomchassis 500 may be made of aluminum and thermal conductivity of aluminumis approximately 130 W/mK.

The heat conduction member 600 is disposed on the external surface ofthe bottom chassis 500 from an area facing the LED unit 360 to an areaspaced apart from the LED unit 360. According to an embodiment of thepresent invention, the difference of heat conductivity between the heatconduction member 600 and the bottom chassis 500 is about 90 W/mK ormore. Accordingly, heat conducted to the bottom chassis 500 from the LEDunit 360 may be quickly exchanged with outside air by the heatconduction member 600. Thermal conductivity of the heat conductionmember 600 is preferably about 220 W/mK or more. In an embodiment of thepresent invention, thermal conductivity of the bottom chassis 500 ispreferably about 130 W/mK or less.

The heat conduction member 600 may comprise graphite, thereby cost orweight may be decreased as compared with a heat conduction member thatuses a metal substance like copper (Cu).

The heat conduction member 600 in an embodiment of the present inventionis a film type and comprises a heat conducting part 602 and an adhesivelayer 601 facing the bottom chassis 500. Since the heat conductionmember 600 and the bottom chassis are easily adhered to each other viathe adhesive layer 601, assembly efficiency and productivity may beimproved. The heat conduction member 600 may be applied to an entirerear surface of the bottom chassis 500, thereby preventing heatconduction from decreasing. The heat conduction member 600 is formedsubstantially in a “U” shape and comprises a first conducting parthaving first and second portions 610, 620 combined with lateral sides521, 522 of the bottom chassis 500 and a second conducting part 630combined with an external surface of a bottom side 510 of the bottomchassis 500. The heat conduction member 600 is preferably a continuousmember that is combined with the external surfaces of the lateral sides521, 522 and the bottom side 510 of the bottom chassis 500.Alternatively, the heat conduction member 600 may have discontinuousparts, to accommodate, for example, discontinuous parts, such ascombining holes (not shown) formed on the bottom chassis 500.

The first and second portions 610, 620 of the first conducting part areformed in a plate shape and correspond to the LED units 360. As shown inFIG. 3, heat generated from each LED unit 360 and passing through thebottom chassis 500 is conducted to the first and second portions 610,620 of the first conducting part and to the second conducting part 630,then, is radiated to outside of the LCD 1. In this case, a thickness(d₁) of the first and second portions 610, 620 of the first conductingpart close to the LED units 360 may be thicker than a thickness (d₂) ofthe second conducting part 630, thereby making heat conductionefficient. Also, manufacturing cost may be reduced by decreasing thethickness (d₂) of the second conducting part 630.

The second conducting part 630 is formed in a plate shape and combinedwith the external surface of the bottom side 510 of the bottom chassis500.

The heat conduction member 600 is formed as a film type and is adheredin a “U” shape to the bottom chassis 500 by a manufacturer.Alternatively, the heat conduction member 600 can be made in a “U” shapeby using a mold.

Referring to FIG. 5, a thermal conduction member 2600 according to anembodiment is formed substantially in an “L” shape. The heat conductionmember 2600 comprises a first conducting part 2610 combined with one ofthe lateral sides 521, 522 of the bottom chassis 500 and a secondconducting part 2620 combined with the bottom side 510 of the bottomchassis 500. The heat conduction member 2600 may be useful when the LEDunit 360 is disposed along one side of the light guiding plate 310.

Referring to FIG. 6, a second conducting part 3630 of a heat conductionmember 3600 according to an embodiment partly covers a rear surface ofthe bottom chassis 500, while the second conducting part 630 of the heatconduction member 600 is formed in a plate shape and covers the entirerear surface of the bottom chassis 500. Thus, a manufacturing costaccording to the present embodiment may be reduced. The heat conductionmember 3600 comprises a rectilinear area 3631 extended in the horizontaldirection from the first and second portions 3610, 3620 of the firstconducting part and oblique areas 3632 extended in the sidewaysdirection from the first and second portions 3610, 3620. A thickness(d₁) of the first and second portions 3610, 3620 close to the LED units360 may be thicker than a thickness (d₂) of the second conducting part3630, thereby making heat conduction efficient. Also, manufacturing costmay be reduced by decreasing the thickness (d₂) of the second conductingpart 3630.

The rectilinear area 3631 is disposed toward a center area of the bottomchassis 500 and the oblique areas 3632 are disposed toward edges of thebottom chassis 500 adjacent to a pair of LED units 360. Accordingly,heat inside of the LCD 1 transfers to the center area or the edges ofthe bottom chassis 500 and may be radiated to the outside of the LCD 1.The form of the second conducting part 3630 may be varied so long asheat conducted from the first and second portions 3610, 3629 of thefirst conducting part is efficiently radiated.

As shown in FIG. 7, a heat conduction member 4600 is formedsubstantially in an “L” shape. The heat conduction member 4600 accordingto an embodiment of the present invention comprises a first conductingpart 4610 combined with one of the lateral sides of the bottom chassis500 and a second conducting part 4630 combined with the bottom side 510of the bottom chassis 500. The heat conduction member 4600 may be usefulwhen the LED unit 360 is disposed along one side of the light guidingplate 310.

In aforementioned embodiments, the first and the second conducting partsare formed as a single body, but may be formed separately. Also, thefirst and the second conducting parts are made of the same substances.Alternatively, the first and second conducting parts may be made ofdifferent substances. In accordance with an embodiment of the presentinvention, thermal conductivity of the first conducting part facing theLED unit is preferably higher than that of the second conducting part.

Although the illustrative embodiments have been described herein withreference to the accompanying drawings, is to be understood that thepresent invention is not limited to those precise embodiments, and thatvarious other changes and modifications may be affected therein by oneof ordinary skill in the related art without departing from the scope orspirit of the invention. All such changes and modifications are intendedto be included within the scope of the invention as defined by theappended claims.

1. A liquid crystal display comprising: a panel on which an image isformed; a light guiding plate disposed behind the panel; a lightemitting diode unit disposed along at least one side of the lightguiding plate, the light emitting diode unit providing light to thepanel; a chassis accommodating the light guiding plate and the lightemitting diode unit; and a heat conduction member disposed across anexternal surface of the chassis from an area facing the light emittingdiode unit to an area apart from the light emitting diode unit, the heatconduction member having a higher thermal conductivity than a thermalconductivity of the chassis.
 2. The liquid crystal display according toclaim 1, wherein the thermal conductivity of the heat conduction memberis at least about 90 W/mK higher than the thermal conductivity of thechassis.
 3. The liquid crystal display according to claim 2, wherein thethermal conductivity of the heat conduction member is greater than orequal to about 220 W/mK.
 4. The liquid crystal display according toclaim 3, wherein the thermal conductivity of the chassis is less than orequal to about 130 W/mK.
 5. The liquid crystal display according toclaim 1, wherein: the chassis is formed in a quadrangular shape andcomprises a bottom side and lateral sides formed by upwardly bendingeach edge of the bottom side; and the heat conduction member comprises afirst conducting part combined with at least one of the lateral sidesand a second conducting part combined with the bottom side.
 6. Theliquid crystal display according to claim 5, wherein light emittingdiode units are disposed at opposite edges of the light guiding plate,and the first conducting-part includes a first portion and a secondportion respectively disposed corresponding to the light emitting diodeunits at the opposite edges.
 7. The liquid crystal display according toclaim 6, wherein the second conducting part comprises a rectilinear areaand an oblique area disposed in an oblique direction from therectilinear area.
 8. The liquid crystal display according to claim 7,wherein the first conducting part is thicker than the second conductingpart.
 9. The liquid crystal display according to claim 8, wherein theheat conduction member is formed by using a mold.
 10. The liquid crystaldisplay according to claim 6, wherein the first conducting part isthicker than the second conducting part.
 11. The liquid crystal displayaccording to claim 1, wherein the heat conduction member is applied toan entire rear surface of the chassis.
 12. The liquid crystal displayaccording to claim 1, wherein the heat conduction member furthercomprises an adhesive layer disposed on the chassis.
 13. The liquidcrystal display according to claim 1, wherein the heat conduction membercomprises graphite.
 14. A heat conduction member for a liquid crystaldisplay comprising: a first conducting part; and a second conductingpart extending from the first conducting part, wherein thermalconductivity of the heat conduction member is greater than or equal toabout 220 W/mK.
 15. The heat conduction member according to claim 14,wherein the first conducting part and the second conducting part have aplate shape and are combined to form a single body having a ‘U’ shape.16. The heat conduction member according to claim 15, wherein the firstconducting part is thicker than the second conducting part.
 17. The heatconduction member according to claim 14, wherein the second conductingpart comprises a rectilinear area and an oblique area disposed in anoblique direction from the rectilinear area.
 18. The heat conductionmember according to claim 17, wherein the first conducting part isthicker than the second conducting part.
 19. The heat conduction memberaccording to claim 14, wherein the heat conduction member comprisesgraphite.